#!/usr/bin/env python

# MS SCEP & SE quarantined files decrypter
# This script is a fork from quarantine.py from the cuckoosandbox project.
# Also thanks to Jon Glass (https://jon.glass/quarantines-junk/)
# Usage: quarantine.py <encryptedfile>
#
# Copyright (C) 2015 KillerInstinct, Optiv, Inc. (brad.spengler@optiv.com)
# This file is part of Cuckoo Sandbox - http://www.cuckoosandbox.org
# See the file 'docs/LICENSE' for copying permission.


#
# Credit: https://raw.githubusercontent.com/brad-accuvant/cuckoo-modified/00ad13c94cc7453c40ed6152d16009ca1c8ed6f2/lib/cuckoo/common/quarantine.py
# Link to license: https://github.com/brad-accuvant/cuckoo-modified/blob/master/docs/LICENSE
#

#
# Hacked up to work as a standalone script by @mariozagaria
#

import os
import sys
import struct
import hashlib
from binascii import crc32

def mse_ksa():
    # hardcoded key obtained from mpengine.dll
    key = [0x1E, 0x87, 0x78, 0x1B, 0x8D, 0xBA, 0xA8, 0x44, 0xCE, 0x69,
           0x70, 0x2C, 0x0C, 0x78, 0xB7, 0x86, 0xA3, 0xF6, 0x23, 0xB7,
           0x38, 0xF5, 0xED, 0xF9, 0xAF, 0x83, 0x53, 0x0F, 0xB3, 0xFC,
           0x54, 0xFA, 0xA2, 0x1E, 0xB9, 0xCF, 0x13, 0x31, 0xFD, 0x0F,
           0x0D, 0xA9, 0x54, 0xF6, 0x87, 0xCB, 0x9E, 0x18, 0x27, 0x96,
           0x97, 0x90, 0x0E, 0x53, 0xFB, 0x31, 0x7C, 0x9C, 0xBC, 0xE4,
           0x8E, 0x23, 0xD0, 0x53, 0x71, 0xEC, 0xC1, 0x59, 0x51, 0xB8,
           0xF3, 0x64, 0x9D, 0x7C, 0xA3, 0x3E, 0xD6, 0x8D, 0xC9, 0x04,
           0x7E, 0x82, 0xC9, 0xBA, 0xAD, 0x97, 0x99, 0xD0, 0xD4, 0x58,
           0xCB, 0x84, 0x7C, 0xA9, 0xFF, 0xBE, 0x3C, 0x8A, 0x77, 0x52,
           0x33, 0x55, 0x7D, 0xDE, 0x13, 0xA8, 0xB1, 0x40, 0x87, 0xCC,
           0x1B, 0xC8, 0xF1, 0x0F, 0x6E, 0xCD, 0xD0, 0x83, 0xA9, 0x59,
           0xCF, 0xF8, 0x4A, 0x9D, 0x1D, 0x50, 0x75, 0x5E, 0x3E, 0x19,
           0x18, 0x18, 0xAF, 0x23, 0xE2, 0x29, 0x35, 0x58, 0x76, 0x6D,
           0x2C, 0x07, 0xE2, 0x57, 0x12, 0xB2, 0xCA, 0x0B, 0x53, 0x5E,
           0xD8, 0xF6, 0xC5, 0x6C, 0xE7, 0x3D, 0x24, 0xBD, 0xD0, 0x29,
           0x17, 0x71, 0x86, 0x1A, 0x54, 0xB4, 0xC2, 0x85, 0xA9, 0xA3,
           0xDB, 0x7A, 0xCA, 0x6D, 0x22, 0x4A, 0xEA, 0xCD, 0x62, 0x1D,
           0xB9, 0xF2, 0xA2, 0x2E, 0xD1, 0xE9, 0xE1, 0x1D, 0x75, 0xBE,
           0xD7, 0xDC, 0x0E, 0xCB, 0x0A, 0x8E, 0x68, 0xA2, 0xFF, 0x12,
           0x63, 0x40, 0x8D, 0xC8, 0x08, 0xDF, 0xFD, 0x16, 0x4B, 0x11,
           0x67, 0x74, 0xCD, 0x0B, 0x9B, 0x8D, 0x05, 0x41, 0x1E, 0xD6,
           0x26, 0x2E, 0x42, 0x9B, 0xA4, 0x95, 0x67, 0x6B, 0x83, 0x98,
           0xDB, 0x2F, 0x35, 0xD3, 0xC1, 0xB9, 0xCE, 0xD5, 0x26, 0x36,
           0xF2, 0x76, 0x5E, 0x1A, 0x95, 0xCB, 0x7C, 0xA4, 0xC3, 0xDD,
           0xAB, 0xDD, 0xBF, 0xF3, 0x82, 0x53
    ]
    sbox = range(256)
    j = 0
    for i in range(256):
        j = (j + sbox[i] + key[i]) % 256
        tmp = sbox[i]
        sbox[i] = sbox[j]
        sbox[j] = tmp
    return sbox

def rc4_decrypt(sbox, data):
    out = bytearray(len(data))
    i = 0
    j = 0
    for k in range(len(data)):
        i = (i + 1) % 256
        j = (j + sbox[i]) % 256
        tmp = sbox[i]
        sbox[i] = sbox[j]
        sbox[j] = tmp
        val = sbox[(sbox[i] + sbox[j]) % 256]
        out[k] = val ^ data[k]

    return out

def mse_unquarantine(f):
    with open(f, "rb") as quarfile:
        data = bytearray(quarfile.read())

    fsize = len(data)
    if fsize < 12 or data[0] != 0x0B or data[1] != 0xad or data[2] != 0x00:
        return None

    sbox = mse_ksa()
    outdata = rc4_decrypt(sbox, data)

    with open(sys.argv[1]+"_decoded_meta.bin", "wb") as f:
        f.write(outdata)

    print sys.argv[1]+"_decoded_meta.bin saved."

    headerlen = 0x28 + struct.unpack("<I", outdata[8:12])[0]
    origlen = struct.unpack("<I", outdata[headerlen-12:headerlen-8])[0]

    #if origlen + headerlen == fsize:
    with open(sys.argv[1]+"_decoded.bin", "wb") as f:
        f.write(outdata[headerlen:])
    print sys.argv[1]+"_decoded.bin saved."

mse_unquarantine(sys.argv[1])